Less than a year into a new IIHS ratings program for front crash prevention, auto manufacturers are making strides in adopting the most beneficial systems with automatic braking capabilities and are offering the features on a wider variety of models. Twenty-one of 24 cars and SUVs, all 2014 models unless noted, earn an advanced or higher rating in the latest round of IIHS evaluations.

"We are already seeing improvements from automakers since the initial launch of our ratings last September," says David Zuby, IIHS executive vice president and chief research officer. "BMW and Lexus, for example, have added more braking capability to their systems, which has paid off in higher ratings."

Large family cars and large luxury cars make up the bulk of the test group. IIHS also tested four midsize luxury/near luxury cars, three midsize luxury SUVs and a midsize SUV.

Four vehicles earn perfect scores when equipped with certain options. They are the BMW 5 series large luxury car, BMW X5 midsize luxury SUV, 2015 Hyundai Genesis large luxury car and Mercedes-Benz E-Class large luxury car. In all, eight models earn the highest rating of superior, 13 earn advanced, and three earn a basic rating.

In addition to familiar luxury brands, consumers will find mainstream nameplates among the newest rated vehicles, including Buick, Chevrolet, Dodge and Toyota.

The Institute rates vehicles as basic, advanced or superior for front crash prevention depending on whether they offer autobrake and, if so, how effective it is in tests at 12 and 25 mph.

Forward collision warning systems that meet performance criteria set by the National Highway Traffic Safety Administration and autobrake systems that provide only minimal speed reduction in IIHS tests earn a basic rating. Vehicles that combine the warning with moderate speed reductions earn an advanced rating. It is possible to qualify for an advanced rating with an autobrake system that doesn't first warn the driver before taking action. Models that offer a warning and provide major speed reduction in IIHS tests earn a superior rating. Some models have multiple ratings because they are available with different versions of front crash prevention systems and their test performance varies. In the current group, this is the case with the BMW 3 series, 5 series and X5.

The rating system is based on HLDI research indicating that forward collision warning and automatic braking systems help drivers avoid front-to-rear crashes (see Status Report special issue: crash avoidance, July 3, 2012).

"We know that this technology is helping drivers avoid crashes," Zuby says. "The advantage of autobrake is that even in cases where a crash can't be avoided entirely, the system will reduce speed. Reducing the speed reduces the amount of damage that occurs to both the striking and struck cars and reduces injuries to people in those cars."

Front crash prevention systems use various types of sensors, such as cameras, radar or laser, to detect when the vehicle is getting too close to one in front of it. Most systems issue a warning and precharge the brakes to maximize their effect if the driver responds by braking. Many systems brake the vehicle autonomously if the driver doesn't respond. In some cases, automatic braking is activated without a warning.

BMW offers an improved front crash prevention system on 2014 models that secures high marks for the X5, 5 series and 3 series. The X5 and 5 series earn superior ratings when equipped with a system that uses both a camera and radar. When the X5, 5 series and 3 series are equipped with an optional camera-only collision mitigation system, they are rated advanced for front crash prevention. The 2 series luxury coupe also earns an advanced rating.

The BMW 5 series brakes for the target in an IIHS test. The car earns a superior rating when equipped with an optional camera and radar system.

In comparison, the 2013 model 3 series was rated basic. The earlier model's system braked for a stopped car ahead only if sensors first detected the car moving before it stopped. The same system is still available on certain 2014 models, and these cars continue to earn a basic rating.

Lexus enhanced its radar-based systems to provide more braking capability, garnering an advanced rating for the GS large luxury car and IS midsize luxury/near-luxury car. Likewise, Toyota made changes to systems on the Highlander midsize SUV and Prius small car to earn advanced ratings in results published earlier. The Toyota Avalon is rated basic because the large family car's autobrake system provided minimal braking in IIHS tests.

The Buick Regal, Cadillac CTS, Cadillac XTS and Chevrolet Impala earn the highest rating of superior when equipped with GM's forward collision warning and autobrake system. The 2014 Buick LaCrosse earns an advanced rating when it has the same system. All of these cars also are available with a warning system only, which earns a basic rating. The cars join the superior-rated Cadillac ATS and SRX, which were included in the first round of tests in 2013 (see "First crash avoidance ratings under new test program: 7 midsize vehicles earn top marks," Sept. 27, 2013).

The Institute's initial batch of front crash prevention ratings covered 74 midsize cars and SUVs. Results for a dozen more models followed last winter, with four earning superior ratings, six earning advanced and two earning basic. Besides the Institute, the European New Car Assessment Programme also rates front crash prevention systems and has so far published ratings for nine models sold in Europe.

Most front crash prevention systems have to be purchased as part of an optional package, but consumers will find that availability is growing, especially for autobrake. More than 20 percent of 2014 models in HLDI's vehicle features database offer a front crash prevention system with autobrake capabilities, twice as many as in 2012. Forward collision warning is offered as an option on nearly 40 percent of 2014 models.

"Sorting through the various trade names and features can be confusing, even if you're looking at models from the same manufacturer. Before buying, consumers should consult the IIHS ratings to find out if the specific model they are considering comes with a top-rated front crash prevention system," Zuby advises.

In addition to ratings for front crash prevention, consumers can consult the HLDI database showing the availability of various crash avoidance features.

Acura, Mercedes-Benz and Volvo sell the systems as standard equipment on certain models. An advanced-rated autobrake system is standard on the Volvo S60, S80 and XC60. Basic-rated forward collision warning is standard on the Acura RLX and ZDX, plus the Mercedes-Benz CLA, E-Class and M-Class.

The Institute will require an advanced or better rating for front crash prevention as one of the criteria needed to win a 2015 Top Safety Pick+ award. For the current 2014 award cycle, models can qualify with a basic rating. Vehicles also must earn good ratings in the moderate overlap front, side, roof strength and head restraint tests, plus a good or acceptable rating in the small overlap front crash test.

Front crash prevention ratings

Large and midsize cars and midsize SUVs (2014 models unless noted)

SUPERIORModels earning a total of 5 to 6 points, based on performance in autobrake tests and credit for forward collision warning.

Autobrake points

Forward collision warning points

TOTAL POINTS

12 mph test

25 mph test

BMW 5 series Collision Warning with braking function

2

3

1

6

BMW X5 Collision Warning with braking function

2

3

1

6

Hyundai Genesis Automatic Emergency Braking 2015 models

2

3

1

6

Mercedes-Benz E-Class Pre-Safe Brake

2

3

1

6

Buick Regal Automatic Collision Preparation

2

2

1

5

Cadillac CTS Automatic Collision Preparation

2

2

1

5

Cadillac XTS Automatic Collision Preparation

2

2

1

5

Chevrolet Impala Collision Mitigation Braking

2

2

1

5

ADVANCEDModels earning a total of 2 to 4 points, based on performance in autobrake tests and credit for forward collision warning.

Autobrake points

Forward collision warning points

TOTAL POINTS

12 mph test

25 mph test

BMW 2 series Collision Warning with City Braking function

2

1

1

4

Buick LaCrosse Automatic Collision Preparation

2

1

1

4

Lexus IS Pre-Collision System

2

1

1

4

Audi A3 Audi Pre Sense Front 2015 models

2

0

1

3

Audi A6 Audi Pre Sense Front

2

0

1

3

BMW 3 series Collision Warning with City Braking function

1

1

1

3

BMW 5 series Collision Warning with City Braking function

1

1

1

3

BMW X5 series Collision Warning with City Braking function

1

1

1

3

Dodge Durango Forward Collision Warning with Crash Mitigation

1

1

1

3

Lexus GS Pre-Collision System

1

1

1

3

Mercedes-Benz CLA Collision Prevention Assist Plus

2

0

1

3

Infiniti QX50 Intelligent Brake Assist

0

1

1

2

Infiniti QX70 Intelligent Brake Assist

0

1

1

2

BASICModels earning 1 point for forward collision warning or in 1 of 2 autobrake tests.